Why This Megillah Was Written
Megillas Rus teaches no laws at all; it was written to show how great the reward is for acts of kindness.
When Naomi blessed her daughters-in-law, she said: may Hashem deal kindly with you, as you dealt with the dead and with me. The Midrash explains the kindness she meant: they had tended to their husbands' shrouds, and they had given up their kesubos so as not to burden her. Rebbi Zeira then makes a striking observation about the whole book. This Megillah, he says, contains nothing about tumah or taharah, nothing forbidden and nothing permitted. Why, then, was it written? To teach how great the reward is for those who do acts of kindness. Rus was kind to Naomi, Boaz was kind to Rus, and from a chain of quiet kindnesses came Oved, Yishai, Dovid HaMelech, and in the end Moshiach.
Source: Midrash Rus Rabbah 2:14 (on Rus 1:8)
Rus's kindness to one lonely widow became the beginning of the royal house of Israel. You will never know where your kindness leads, but you can begin it. This week, choose someone who is carrying a loss or living alone, an older relative, a widowed neighbor, a new family in shul. Call, visit, or bring something to eat, and do it again the following week. Kindness that continues, like Rus's, is the kind that builds.